Lead Sources to the Amundsen Sea, West Antarctica

The global prevalence of industrial lead (Pb) contamination was exemplified decades ago by the predominance of anthropogenic Pb in samples of Antarctic surface ice and in Southern Ocean surface waters. Decreases in environmental Pb contamination corresponding with the near-global phase-out of leaded automobile gasoline beginning in the 1970s have since been observed. Measurements of Pb concentration in snow and ice core samples from Antarctica show that recent fluxes of industrial Pb to Antarctica have similarly declined. Here, we present measurements of Pb concentrations and isotopic compositions in seawater and surface sediments from the Amundsen Sea continental shelf including the Amundsen Sea Polynya. Both sets of measurements show that most (∼60–95%) of the Pb at our sites, at the time of sampling, is natural in source: that is, derived from the weathering of Antarctic continental rocks. These fluxes of natural Pb then become entrained into polynya waters either from sediment resuspension or from the transport of sediment-laden glacial melt waters to the polynya.

全球工业铅（Pb）污染的广泛程度，在数十年前便通过南极地表冰与南大洋表层海水样本中人为源铅（anthropogenic Pb）占绝对主导的现象得到佐证。自20世纪70年代全球近乎全面淘汰含铅车用汽油以来，环境铅污染水平的下降已被观测证实。对南极雪冰岩芯样本的铅浓度测量结果显示，近期输入南极的工业铅通量同样呈下降趋势。本研究报道了阿蒙森海大陆架区域（含阿蒙森海冰间湖（Amundsen Sea Polynya））内海水与表层沉积物的铅浓度及同位素组成数据。两类测量结果均表明，采样时段内研究站位中约60%~95%的铅为天然来源，即源自南极大陆岩石的风化作用。这些天然铅通量随后通过沉积物再悬浮，或是携带着沉积物的冰川融水向冰间湖输送的过程，被裹挟进入冰间湖水体中。